This invention concerns rotation indicator means, that is to say a position indicator assembly for use with first and second members which are or are to be rotationally engaged with each other, particularly where one member is to be threadedly engaged into or onto the other member, and more particularly where that one member is a bolt or a nut, respectively.
According to the present invention such an assembly comprises a first element which is permanently secured to either the nut or the bolt and a second element which is adapted to be releasably and non-rotatably mounted on or in the first element in a selected one of a plurality of positions and incorporates means of indicating its rotational position relative to a reference.
In embodiments of the invention presently envisaged the first and second members may comprise a nut and a bolt, or vice versa, or a nut and a threaded stud projecting from a larger substrate, or a bolt and a threaded bore in a larger substrate.
The first element will, however, always be secured to or formed integrally with either the nut or the bolt.
In a specific practical embodiment the first element may conveniently comprise an insert, e.g of nylon, fixed inside the bore of a nut, as in a lock nut, but with a protruding portion serving as a carrier or mounting means for the second element, which incorporates some form of indicia to indicate the position thereof relative to the third element, which comprises a marker of some sort held in place by the aforesaid nut.
In alternative embodiments, the insert may not protrude, in which case it will be apertured and the second element will engage inside it.
In other practical embodiments the first element may be formed integrally on the nut (and need not protrude) or it may take the form of an external fitment.
Equivalent embodiments to all the foregoing may be applied to the head of a bolt.
The invention can, of course, be applied to any shape or size of nut or bolt.
The invention can usefully be applied in cases where the nut or the bolt head is large or the space surrounding the nut and/or bolt is confined, in which cases the first element of the assembly can be an insert of relatively small diameter on or in which the indicator element (second element) can be mounted.
The second element may additionally serve as a cap or cover when fitted on or in the first element. Alternatively, the second element may itself be formed in two parts, one part being a separable cap or cover, which may carry the means indicating the rotational position of the second element.
The reference may advantageously be provided by a third element of the assembly which is adapted to be secured in position by either the nut or the bolt. In this respect, the third element can be a washer or a modified washer which is held in position by, or at least partially by, the nut or the bolt.
In embodiments where a third element is not provided, the reference may be provided by an external feature, such as an adjacent nut or bolt, or the pointer on an adjacent indicator assembly, or simply a mark applied on the adjacent substrate.